Component for flow rate control device, and fuel injection valve

ABSTRACT

An object of the present invention is to provide a fluid control device with an improved effect of suppressing blowhole generation. Therefore, a component for a flow rate control device of the present invention includes: a first component  140  (A); a second component  107  (B) fixed to the first component by a press-fitting portion  802 ; a butt-welded portion  803  connecting the first component and the second component; and a first gap  1001  and a second gap  1002  formed between mutually opposing surfaces of the first component and the second component. The first gap is provided on a side of the press-fitting portion with respect to the second gap between the press-fitting portion and the butt-welded portion, and is formed in a direction intersecting a press-fitting direction. The second gap is provided on a side of the butt-welded portion with respect to the first gap between the press-fitting portion and the welded portion, and is formed in a direction intersecting the first gap.

TECHNICAL FIELD

The present invention relates to a flow rate control device thatcontrols a flow rate.

BACKGROUND ART

Examples of the related art for flow rate control devices are anelectromagnetic fuel injection valve device described in JP H11-193762 A(PTL 1) and an electromagnetic fuel injection valve described in JP2013-160083 A (PTL 2).

In the electromagnetic fuel injection valve device of PTL 1, a movablevalve is formed of an electromagnetic core and a movable needle havingdifferent material compositions, and both the members are welded andjoined. In the movable valve, an end surface of the electromagnetic coreand the movable needle are butt-welded to each other, and a meltedportion is formed such that a weld penetration depth is larger than alength of a butt surface (see, for example, claims 1 and 2 and FIG. 2).

The fuel injection valve of PTL 2 is the electromagnetic fuel injectionvalve including: a nozzle tube having an injection hole for ejectingfuel at a distal end; a fixed core that is press-fitted into an innerperipheral portion of the nozzle tube and has an outer peripheralportion forming a fitting portion with the inner peripheral portion; amovable core that is arranged in the nozzle tube, faces the fixed core,and is capable of reciprocating in the nozzle tube; a valve body that isdriven by the movable core to open and close the injection hole; and anelectromagnetic coil that is arranged on the outer circumference of thenozzle tube and electromagnetically drives the movable core. An annularnon-fitting portion (annular gap) is formed in a part of the fittingportion, and the nozzle tube and the fixed core are welded and joined atthis non-fitting portion to eliminate a welding defect caused byevaporation of a lubricant (see Abstract, claim 1, and FIGS. 4 and 9).The annular gap mitigates the vapor pressure by its volume andcontributes to suppression of generation of the welding defect (seeparagraph 0053). In the fuel injection valve of PTL 2, the lubricant isapplied to the inner peripheral portion of the nozzle tube, and thelubricant is scraped off at the fitting portion at the time of pressfitting to prevent the lubricant from entering the annular gap (seeparagraph 0055).

CITATION LIST Patent Literature

-   PTL 1: JP H11-193762 A-   PTL 2: JP 2013-160083 A

SUMMARY OF INVENTION Technical Problem

The electromagnetic fuel injection valve device of PTL 1 and theelectromagnetic fuel injection valve of PTL 2 are examples of a flowrate control device. Hereinafter, the electromagnetic fuel injectionvalve device of PTL 1 and the electromagnetic fuel injection valve ofPTL 2 will be simply referred to as the fuel injection valve fordescription.

In PTL 1, it is considered to improve durability by making the weldpenetration depth larger than the length of the butt surface of abutt-welded portion, but there is no consideration regarding generationof a blowhole due to vaporization of the lubricant during welding causedby adhesion or entry of the lubricant to a planned weld portion.

In the fuel injection valve of PTL 2, it is considered to suppress thelubricant from entering the annular gap where the welded portion isprovided, but the fitting portion to which the lubricant adheres comesinto contact with the inner peripheral surface of the nozzle tube wherethe welded portion is provided, and no configuration capable ofsupporting butt welding is provided.

Two components to be butt-welded are press-fitted and fixed beforewelding. A lubricant is applied to areas to be press-fit before pressfitting, but the lubricant is vaporized during welding and a blowhole isgenerated as described in PTL 2 if the lubricant adheres to or entersthe planned weld portion.

In the fuel injection valve of PTL 2, it is considered to suppress thelubricant from entering the annular gap where the welded portion isprovided, but the fitting portion to which the lubricant adheres comesinto contact with the inner peripheral surface of the nozzle tube wherethe welded portion is provided, and there is a demand for a technique offurther improving the effect of suppressing the blowhole generation.

An object of the present invention is to provide a component of a fluidcontrol device with an improved effect of suppressing blowholegeneration.

Solution to Problem

In order to achieve the above object, the present invention provides aflow rate control device including: a first component; a secondcomponent fitted with the first component by a press-fitting portion; anabutting surface that comes into contact with one surface of the firstcomponent and an opposing surface of the second component therebetween;and a welded portion formed along the abutting surface on the abuttingsurface of the first component and the second component. A first gap isformed by the first component and the second component among apress-fitting fitting portion between the first component and the secondcomponent, an abutment, and a welded portion. A second gap is formed bythe first component and the second component among the first gap, theabutment, the welded portion. The first gap is formed in a directionintersecting a press-fitting direction, the second gap is formed in adirection intersecting the abutment direction, and the first gap islarger than the second gap.

Advantageous Effects of Invention

According to the present invention, it is possible to provide the fluidcontrol device with the improved effect of suppressing the blowholegeneration. Other objects, configurations, and effects which have notbeen described above become apparent from embodiments to be describedhereinafter.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a cross-sectional view partially illustrating a fuelinjection valve 1 and a fuel pipe 211 according to an embodiment of thepresent invention.

FIG. 1B is a cross-sectional view illustrating a connection structuredifferent from that of FIG. 1A regarding a connection structure betweenthe fuel injection valve 1 and the fuel pipe 211 according to theembodiment of the present invention.

FIG. 2 is a graph illustrating the relationship between a fuel pressureinside the fuel injection valve and a load (calculated value) applied ina direction of the central axis 1 a of the fuel injection valve 1.

FIG. 3 is a cross-sectional view illustrating an assembly of an adapter140 and a fixed core 107 that form the fuel injection valve 1.

FIG. 4 is an enlarged cross-sectional view of a welded portion between afixed core 407 and an injection hole cup support body 401 according toComparative Example 1 of the present invention.

FIG. 5A is an enlarged cross-sectional view of a welded portion betweena first component A and a second component B according to ComparativeExample 2 of the present invention.

FIG. 5B is an enlarged cross-sectional view of a welded portion betweena first component A and a second component B according to ComparativeExample 3 of the present invention.

FIG. 5C is an enlarged cross-sectional view of a welded portion betweena first component A and a second component B according to ComparativeExample 4 of the present invention.

FIG. 6 is an enlarged cross-sectional view illustrating a state beforepress fitting of a fixed core 607 and an adapter 640 according toComparative Example 5 of the present invention.

FIG. 7 is an enlarged cross-sectional view of a welded portion between afirst component A and a second component B according to ComparativeExample 6 of the present invention.

FIG. 8 is an enlarged cross-sectional view of a welded portion betweenan adapter 140 and a fixed core 107 according to the embodiment of thepresent invention.

FIG. 9 is an enlarged cross-sectional view illustrating a state beforepress fitting of the fixed core 107 and the adapter 140 according to theembodiment of the present invention.

FIG. 10 is an enlarged cross-sectional view of the welded portionbetween the adapter 140 and the fixed core 107 according to theembodiment of the present invention.

FIG. 11 is an enlarged cross-sectional view of a welded portion betweenan adapter 140 and a fixed core 107 according to Comparative Example 7of the present invention.

FIG. 12 is an enlarged cross-sectional view of a welded portion betweenthe adapter 140 and the fixed core 107 according to a modification ofthe present invention.

FIG. 13 is a conceptual view illustrating a configuration of a first gap1001 and a second gap 1002.

DESCRIPTION OF EMBODIMENTS

Hereinafter, specific modes for carrying out the present invention willbe described with reference to the drawings.

Hereinafter, an embodiment of a flow rate control device of the presentinvention will be described with reference to the drawings. In thepresent embodiment, a fuel injection valve (fuel injection device) willbe described as an example of the flow rate control device, but thepresent invention is not limited thereto. For example, the flow ratecontrol device may be a high-pressure fuel pump in which large stress isgenerated in a welded portion due to high fuel pressure. Note that, inthe drawings, a size of a component or a size of a gap is sometimesexaggerated as compared with its actual ratio in order to facilitateunderstanding of a function, and an unnecessary component is sometimesomitted in order to describe the function. In the embodiment andcomparative examples to be described below, the same reference signs aregiven to constituent elements of the same type. In the embodiment andcomparative examples according to the present invention, differentpoints will be mainly described, and the redundant description will beomitted.

First, an outline of a configuration of the fuel injection valveaccording to the present embodiment will be described with reference toFIG. 1. FIG. 1A is a cross-sectional view partially illustrating a fuelinjection valve 1 and a fuel pipe 211 according to the presentembodiment.

In the following description, an up-and-down direction is defined anddescribed based on FIG. 1A, but this up-and-down direction does notlimit an up=and-down direction in a mounting state of the fuel injectionvalve 1. The fuel injection valve 1 is provided with a fuel supply port118 at an upper end portion and a fuel injection hole 117 at a lower endportion. There is a case where a side where the fuel supply port 118 isprovided is referred to as a proximal end, and a side where the fuelinjection hole 117 is provided is referred to as a distal end fordescription.

As illustrated in FIG. 1, in the fuel injection valve 1, for example, amover portion 114 includes a cylindrical movable core (mover) 102 and aneedle valve 114A (valve body) located at the center of the movable core102. A gap is provided between an end surface of a fixed core (stator)107 having a fuel introduction hole for guiding fuel to the center andan end surface of the movable core 102. An electromagnetic coil 105(solenoid) that supplies a magnetic flux is provided in a magnetic pathincluding the gap. In other words, the fixed core 107 is arranged so asto oppose the movable core 102 as illustrated in FIG. 1.

The movable core 102 is attracted toward the fixed core 107 to drive themovable core 102 by a magnetic attraction force generated between theend surface of the movable core 102 and the end surface of the fixedcore 107 due to the magnetic flux passing through the gap, and theneedle valve 114A is separated from a valve seat portion 39 (valve seat)to open a fuel passage provided in the valve seat portion 39. In otherwords, the movable core 102 drives the needle valve 114A (valve body).

The amount of injected fuel is mainly determined depending on a pressuredifference between a fuel pressure and an atmospheric pressure at aninjection opening of the fuel injection valve 1 and a time for whichfuel is injected with the needle valve 114A kept open.

When the energization of the electromagnetic coil 105 is stopped, themagnetic attraction force acting on the movable core 102 disappears, theneedle valve 114A and the movable core 102 move in a closing directiondue to a biasing force of an elastic member 110 that biases the needlevalve 114A in the closing direction and a pressure drop caused by theflow velocity of fuel flowing between the needle valve 114A and thevalve seat portion 39. When the needle valve 114A is seated on the valveseat portion 39, the fuel passage is closed. The fuel is sealed by thecontact between the needle valve 114A and the valve seat portion 39 sothat the fuel is prevented from leaking from the fuel injection valve 1at an unintended timing.

In an internal combustion engine, attempts have been made to increasethe injection pressure of fuel from the conventional 20 MPa to, forexample, about 35 MPa, reduce a droplet size of the fuel injected from afuel injection valve, and promote vaporization.

When the fuel pressure is increased, stress generated in a member (fuelpressure holding member) that holds the fuel pressure inside the fuelinjection valve increases. In order to allow the fuel pressure holdingmember to have a margin of strength against the stress generated at thehigh fuel pressure, it is advantageous to select a material having highyield stress and tensile strength.

Meanwhile, since the fixed core 107 of the fuel injection valve 1 formsa part of the electromagnetic solenoid, a material having excellentmagnetic characteristics is used. In general, the material havingexcellent magnetic characteristics has low yield stress and tensilestrength. Therefore, the material used for the fixed core 107 isunsuitable for use in a connecting portion with the fuel pipe 211, whichrequires a small thickness and high rigidity.

Accordingly, in the fuel injection valve 1 supporting the high fuelpressure, the connecting portion with the fuel pipe 211 is configuredusing the adapter 140 which is a separate component from the fixed core107, and is divided into two components, that is, the fixed core 107 andthe adapter 140. The fuel supply port 118 is formed at an end portion ofthe adapter 140 on a side opposite to the fixed core 107 side. Theadapter 140 is made of a material having higher yield stress and tensilestrength than the fixed core 107, and the fixed core 107 is made of amaterial having excellent magnetic characteristics. The two componentsare press-fitted in a valve axis direction (direction along the centralaxis 1 a), and then, welded over the entire circumference at 403 a andfixed.

Therefore, the fuel injection valve that ensures the strength against anincrease in fuel pressure without causing deterioration of the magneticcharacteristics of the fixed core 107 can be manufactured while anincrease in cost is suppressed.

For the same reason, the fixed core 107 and the injection hole cupsupport body (nozzle holder) 101 are divided into two components, amaterial having higher yield stress and tensile strength than the fixedcore 107 is used for the injection hole cup support body 101, and amaterial having excellent magnetic characteristics is used for the fixedcore 107. The two components are press-fitted in the direction of thecentral axis 1 a so as to be pressed against each other in the radialdirection, and then, welded over the entire circumference at 403 b andfixed.

In the upper part of FIG. 1A, a load acting in the direction of thecentral axis 1 a of the fuel injection valve 1 due to the fuel pressureis schematically illustrated by an arrow 214. Since the fuel injectionvalve 1 is connected to the fuel pipe 211 and the fuel is sealed by anO-ring 212, an inside 213 of the fuel pipe 211 and an inside of the fuelinjection valve 1 are filled with high-pressure fuel. A cross-sectionalarea of the fuel pipe 211 is determined by an inner diameter φR of thefuel pipe 211, and the product of the cross-sectional area of the fuelpipe 211 and the fuel pressure is defined as a fuel pressure load.

Since the fuel pipe 211 is fixed to an engine (not illustrated), thefuel injection valve 1 receives the fuel pressure load in a direction ofthe arrow 214. Since the fuel injection valve 1 is in contact with theengine (not illustrated) at a tapered surface 215 of a housing 103, forexample, the above-described fuel pressure load is transmitted throughthe adapter 140, the fixed core 107, the injection hole cup support body101, and the housing 103 that constitute the fuel injection valve 1.

FIG. 1B is a cross-sectional view illustrating a connection structuredifferent from that of FIG. 1A regarding a connection structure betweenthe fuel injection valve 1 and the fuel pipe 211 according to theembodiment of the present invention.

In the fuel injection valve 1 illustrated in FIG. 1B, a mode in whichthe fuel injection valve 1 can be suspended from the fuel pipe 211 via aplate 251 is illustrated as a mode different from the connectionstructure between the fuel injection valve 1 and the fuel pipe 211illustrated in FIG. 1A.

FIG. 2 is a graph illustrating the relationship between a fuel pressureinside the fuel injection valve and a load (calculated value) applied inthe direction of the central axis 1 a of the fuel injection valve 1.

Conventionally, a maximum fuel pressure is, for example, 20 MPa, and aload (axial load) applied in the direction of the central axis 1 a ofthe fuel injection valve 1 by the fuel pressure of 20 MPa is, forexample, 1800 N. The fuel pressure is likely to be further increased to35 MPa, an axial load in such a case becomes approximately 3200 N, whichis 1.5 times of the former. Further, in a system assuming the fuelpressure of 35 MPa, for example, it is necessary to maintain thestructural strength up to a fuel pressure of 55 MPa in consideration ofa safety margin, and an axial load in such a case reaches approximately7700 N. Since the axial load depending on the fuel pressure istransmitted to components forming the fuel injection valve 1, stressgenerated in each component increases as the fuel pressure increases. Ifshapes, materials, and weld shapes of the components forming the fuelinjection valve 1 are not changed from the conventional components, themargin of strength decreases. On the other hand, the use of a materialhaving high strength or a complicated welding method leads to anincrease in cost. FIG. 3 is a cross-sectional view illustrating anassembly of the adapter 140 and the fixed core 107 that form the fuelinjection valve 1.

Since the thickness of an O-ring mounting portion 250 of the adapter 140is small, a material is selected with priority on strength. The adapter140 can withstand the stress generated at the fuel pressure of 35 MPa.The fixed core 107 is a component constituting a magnetic circuit, anddoes not have a thin portion like the O-ring mounting portion 250.Accordingly, a material having excellent magnetic characteristics isselected for the fixed core 107. The fixed core 107 has a largethickness, and thus, can withstand the stress generated at the fuelpressure of 35 MPa even if a material having low strength is selected.

In other words, a saturation magnetic flux density of the fixed core 107(stator) is higher than a saturation magnetic flux density of theadapter 140 (pipe). The adapter 140 is configured using a memberseparate from the fixed core 107, and is directly press-fitted and fixedto the fixed core 107. As a result, for example, the manufacturing costof the adapter 140 can be reduced while ensuring the magneticcharacteristics of the fixed core 107.

Here, the tensile strength of the fixed core 107 (stator) is lower thanthe tensile strength of the adapter 140 (pipe). As a result, forexample, it becomes possible to easily process the fixed core 107 whileensuring the strength of the adapter 140 even if a shape of the fixedcore 107 is complicated.

In the present embodiment, a welded portion between the adapter 140which is the first component and the fixed core 107 which is the secondcomponent is a butt-welded portion having a butt-joint configuration.Butt portions of the adapter 140 and the fixed core 107 need to preventthe leakage of high-pressure fuel filling the inside the fuel injectionvalve.

A mounting portion 301 of the adapter 140 of the fuel injection valveand a mounting portion 302 of the fixed core 107 are press-fitted so asto make radial contact, and butt welding is performed on the entirecircumference at a butt-welded portion 303 to seal the fuel. Since themounting portion 301 of the adapter 140 and the mounting portion 302 ofthe fixed core 107 are press-fitted and fixed before welding, it ispossible to suppress collapse of the adapter 140 caused by straingenerated during welding.

In other words, the fixed core 107 (stator) has the mounting portion(stator-side mounting portion) 302 on the upstream side in a fuel flowdirection, and the adapter 140 (pipe) has the mounting portion(adapter-side mounting portion or pipe-side mounting portion) 301 on thedownstream side. The mounting portion 302 and the mounting portion 301are brought into direct contact and press-fitted with each other in theradial direction. The mounting portion 302 and the mounting portion 301can be easily manufactured by cutting or the like, and a sealingproperty of high-pressure fuel is improved by fixing the mountingportion 302 and the mounting portion 301 by press fitting and buttwelding.

Further, a downstream distal end portion 301 a of the mounting portion301 is butted so as to come into contact with an upper surface (upstreamsurface) of the mounting portion 302, and butt welding is performed atthis contact portion. Specifically, the mounting portion 301 is locatedon the outer peripheral side (radially outer side) of the mountingportion 302, the downstream distal end portion 301 a of the mountingportion 301 comes into contact with the fixed core 107 in the directionof the central axis 1 a, and is butt-welded at this contact portion.

As a result, the butt welding between the mounting portion 302 and themounting portion 301 is possible, and both the mounting portion 302 andthe mounting portion 301 can be firmly fixed at low cost. Since thematerial used for the adapter 140 has higher strength than the fixedcore 107, it makes sense to arrange the adapter 140 on the outerperipheral side where stress is high. Further, in the case of a materialhaving high strength, the thickness can be made thin, and welding fromthe outer peripheral side is easy.

Here, the fixed core 107 has a protruding portion 107 a (brim portion)that protrudes to the outer peripheral side on the downstream side (theside opposite to the adapter 140 side, the opposite side of the adapter140) of the mounting portion 302. The protruding portion 107 a is formedintegrally with a member forming the fixed core 107.

The protruding portion 107 a (brim portion) forms a magnetic pathagainst an end portion (upper end) of the housing 103 opposing theprotruding portion 107 a, and forms a magnetic circuit 140M (see FIG.1A).

As illustrated in FIG. 1B, when the fuel injection valve is connected tothe fuel pipe 211 via the plate 251, the fixed core 107 is pulleddownstream with respect to the adapter 140 by the fuel pressure load dueto the fuel pressure inside the fuel injection valve. In both the caseof FIG. 1A and the case of FIG. 1B, the two components of the adapter140 and the fixed core 107 are press-fitted in the radial direction, andthen, welded over the entire circumference and fixed in the fuelinjection valve 1. Since a load applied to such a welded and fixedportion increases with the fuel pressure, it is necessary to provide theinexpensive fuel injection valve 1 by ensuring the welding strengthcapable of withstanding a high fuel pressure with the minimum necessarywelding.

Next, an operation of the fuel injection valve will be described usingFIG. 1A.

The injection hole cup support body 101 includes a small-diametertubular portion 101A having a small diameter and a large-diametertubular portion 101B having a large diameter. A guide portion 115 and aninjection hole cup (fuel injection hole forming member) 116 having thefuel injection hole 117 are inserted or press-fitted inside a distalportion of the small-diameter tubular portion 101A, and an outerperipheral edge of a distal end surface of the injection hole cup 116 iswelded to the small-diameter tubular portion 101A over the entirecircumference. As a result, the injection hole cup 116 is fixed to thesmall-diameter tubular portion 22. The guide portion 115 has a functionof guiding an outer circumference of a valve body distal end portion114B when the valve body distal end portion 114B provided at a distalend of the needle valve 114A constituting the mover portion 114 moves upand down in the direction of the central axis 1 a of the fuel injectionvalve 1.

A conical valve seat portion 39 is formed in the injection hole cup 116on the downstream side of the guide portion 115. The valve body distalend portion 114B provided at the distal end of the needle valve 114Aabuts on or separates from the valve seat portion 39, thereby blockingthe flow of fuel or guiding the fuel to the fuel injection hole. Agroove is formed at the outer circumference of the injection hole cupsupport body 101, and a seal member of a combustion gas, represented bya tip seal 131 made of resin, is fitted into this groove.

A needle valve guide portion 113 that guides the needle valve 114Aconstituting the mover is provided at an inner peripheral lower endportion of the fixed core 107. The needle valve 114A is provided with aguide portion 127. Although not illustrated, the guide portion 127 ispartially provided with a chamfer, and the chamfer forms the fuelpassage. The needle valve 114A having an elongated shape has its radialposition regulated by the needle valve guide portion 113, and is guidedso as to reciprocate straight in the direction of the central axis 1 a.Note that a valve opening direction is upward in the direction of thecentral axis 1 a, and a valve closing direction is downward in thedirection of the central axis 1 a.

A head portion 114C, which includes a stepped portion 129 having anouter diameter larger than a diameter of the needle valve 114A, isprovided in an end portion of the needle valve 114A on the opposite sideof an end portion in which the valve body distal end portion 114B isprovided. A seating surface of a spring (first spring) 110 that biasesthe needle valve 114A in the valve closing direction is provided on anupper end surface of the stepped portion 129.

The mover portion 114 has the movable core 102 having a through-hole102A through which the needle valve 114A penetrates at the center. Azero spring (second spring) 112 that biases the movable core 102 in thevalve opening direction is held between the movable core 102 and theneedle valve guide portion 113.

Since a diameter of the through-hole 102A is smaller than a diameter ofthe stepped portion 129 of the head portion 114C, an upper side surfaceof the movable core 102 held by the zero spring 112 and a lower endsurface of the stepped portion 129 of the needle valve 114A abut on eachother, and engage with each other under the action of the biasing forceof the spring 110 that presses the needle valve 114A toward the valveseat portion 39 of the injection hole cup 116.

As a result, the movable core 102 and the needle valve 114A movetogether with respect to the upward movement of the movable core 102against the biasing force of the zero spring 112 or the downwardmovement of the needle valve 114A along the biasing force of the zerospring 112. However, the needle valve 114A and the movable core 102 canmove in different directions when a force that moves the needle valve114A upward or a force that moves the movable core 102 downwardindependently acts on both the needle valve 114A and the movable core102 regardless of the biasing force of the zero spring 112.

The fixed core 107 is press-fitted into an inner peripheral portion ofthe large-diameter tubular portion 101B of the injection hole cupsupport body 101, and is welded and joined at a press-fitting contactposition. With such welding and joining, a gap formed between the insideof the large-diameter tubular portion 101B of the injection hole cupsupport body 101 and the outside air is sealed. The fixed core 107 isprovided with a through-hole 107D having a diameter φCn at the center asa fuel introduction passage.

In other words, the adapter 140 and the fixed core 107 are fixed to eachother in the state where a lower surface (surface on the downstreamside) of the adapter 140 and an upper surface (surface on the upstreamside) of the fixed core 107 are in direct contact with each other bypress fitting.

A lower end of the spring 110 abuts on a spring receiving surface formedon an upper end surface of the stepped portion 129 of the needle valve114A, and the other end of the spring 110 is received by an adjuster 54.

As a result, the spring 110 is held between the head portion 114C andthe adjuster 54. It is possible to adjust the initial load by which thespring 110 presses the needle valve 114A against the valve seat portion39 by adjusting the fixing position of the adjuster 54 in the directionof the central axis 1 a.

The cup-shaped housing 103 is fixed to the outer circumference of thelarge-diameter tubular portion 101B of the injection hole cup supportbody 101. A through-hole is provided at the center of a bottom of thehousing 103, and the large-diameter tubular portion 101B of theinjection hole cup support body 101 is inserted into the through-hole.An outer peripheral wall portion of the housing 103 forms an outerperipheral yoke portion that opposes an outer peripheral surface of thelarge-diameter tubular portion 101B of the injection hole cup supportbody 101.

The electromagnetic coil 105 wound in an annular shape is arrangedinside a tubular space formed by the housing 103. The electromagneticcoil 105 is formed of an annular coil bobbin 104 and a copper wire woundaround the coil bobbin 104. A conductor 109 having rigidity is fixed towinding-start and winding-finish end portions of the electromagneticcoil 105, and led out from the through-hole provided in the protrudingportion 107 a of the fixed core 107.

Each outer circumference of the conductor 109, the fixed core 107, andthe large-diameter tubular portion 101B of the injection hole cupsupport body 101 is molded by injecting insulating resin from an upperend opening portion of the housing 103 along the inner circumference,and is covered by a resin-molded body 121.

A plug to supply power from a high-voltage power supply or a batterypower supply is connected to a connector 43A formed at a distal endportion of the conductor 109, and energization and non-energization arecontrolled by a controller (not illustrated). During energization of theelectromagnetic coil 105, a magnetic attraction force is generatedbetween the movable core 102 and the fixed core 107 of the mover portion114 in a magnetic attraction gap by the magnetic flux passing throughthe magnetic circuit 140M, and the movable core 102 is moved upward bybeing attracted by a force exceeding a set load of the spring 110.

At this time, the movable core 102 engages with the head portion 114C ofthe needle valve 114A to move upward together with the needle valve114A, and moves until an upper end surface of the movable core 102 abutson a lower end surface of the fixed core 107. As a result, the valvebody distal end portion 114B of the needle valve 114A separates from thevalve seat portion 39, and the fuel passes through the fuel passageformed between the valve body distal end portion 114B and the valve seatportion 39 is injected from the fuel injection hole 117 at the distalend of the injection hole cup 116 into a combustion chamber of theinternal combustion engine.

While the valve body distal end portion 114B of the needle valve 114Aseparates from the valve seat portion 39 and is pulled upward, theelongated needle valve 114A is guided to reciprocate straight along thedirection of the central axis 1 a by two sites of the needle valve guideportion 113 and the guide portion 115 of the injection hole cup 116.

When the energization to the electromagnetic coil 105 is cut off, themagnetic flux disappears so that the magnetic attraction force in themagnetic attraction gap also disappears. In this state, the spring forceof the spring 110 overcomes the force of the zero spring 112 and acts onthe entire mover portion 114 (the mover 102 and the needle valve 114A).As a result, the mover portion 114 is pushed back by the spring force ofthe spring 110 to a valve closing position where the valve body distalend portion 114B comes into contact with the valve seat portion 39.

While the valve body distal end portion 114B comes into contact with thevalve seat portion 39 to be located at the valve closing position, theneedle valve 114A is guided only by the needle valve guide portion 113and does not come into contact with the guide portion 115 of theinjection hole cup 116.

At this time, the stepped portion 129 of the head portion 114C abuts onthe upper surface of the movable core 102 to move the movable core 102downward (in the valve closing direction) by overcoming the force of thezero spring 112. When the valve body distal end portion 114B collideswith the valve seat portion 39, the movable core 102 continues to movedownward (in the valve closing direction) due to inertial force sincethe movable core 102 is the separate body from the needle valve 114A. Atthis time, friction due to fluid occurs between the outer circumferenceof the needle valve 114A and the inner circumference of the movable core102, and the energy of the needle valve 114A that rebounds from thevalve seat portion 39 in the valve opening direction is absorbed.

Since the movable core 102 having a large inertial mass is separatedfrom the needle valve 114A, the rebound energy itself is also small.Further, the inertia force of the movable core 102 that has absorbed therebound energy of the needle valve 114A is reduced by the absorptionamount, and a repulsive force received after compressing the zero spring112 also decreases, and thus, a phenomenon in which the needle valve114A is moved again in the valve opening direction due to the reboundphenomenon of the movable core 102 is unlikely to occur. Thus, therebound of the needle valve 114A is suppressed to the minimum, and aso-called secondary injection phenomenon in which the valve is openafter the energization of the electromagnetic coil 105 is cut off andfuel is randomly injected is suppressed.

COMPARATIVE EXAMPLES

Next, problems of fuel injection valves according to comparativeexamples of the present invention will be described with reference toFIGS. 4 to 7.

FIG. 4 is an enlarged cross-sectional view of a welded portion between afixed core 407 and an injection hole cup support body 401 according toComparative Example 1 of the present invention. Note that FIG. 4 is anenlarged view of part IV of FIG. 1A.

The fixed core 407 is press-fitted into the injection hole cup supportbody 401, and then, joined to the injection hole cup support body 401 bylap welding.

Due to a fuel pressure, the injection hole cup support body 401 receivesloads to the radially outer side and downward in the direction of thecentral axis 1 a of the fuel injection valve 1, but the fixed core 407is fixed in the direction of the central axis 1 a, and thus, the loadthat mainly acts on a lap-welded portion 402 is a load 404 received bythe injection hole cup support body 401 downward in the direction of thecentral axis 1 a of the fuel injection valve 1.

When a boundary surface during the lap welding of the fixed core 407 andthe injection hole cup support body 401 is denoted by 403, a shear loadis generated on the boundary surface 403. High stress is generated at anupper end 403A of the boundary surface 403 due to the shear load. Thisis because the stress is concentrated on the upper end 403A when theload downward in the direction of the central axis 1 a of the fuelinjection valve 1 is applied to the injection hole cup support body 401even if the length of the boundary surface 403 during the lap welding isincreased.

When the fuel pressure is 20 MPa, an axial load is small as illustratedin FIG. 2, and thus, the stress generated at the upper end 403A of theboundary surface 403 is relatively small, and sufficient strength can besecured.

On the other hand, when the fuel pressure of, for example, 35 MPa,higher than the conventional one, is used, the axial load increases asillustrated in FIG. 2. Accordingly, the stress generated at a base metaland a welding boundary portion also increases due to the shearing forcesince a load direction and a base metal boundary are parallel to eachother in the lap welding, and there is a possibility that it isdifficult to ensure sufficient strength. FIG. 5A is an enlargedcross-sectional view of a welded portion between a fixed core B and anadapter A according to Comparative Example 2 of the present invention.FIG. 5A illustrates a shape of a melted and re-solidified portion(hereinafter referred to as a melted portion) when a butt portionbetween the fixed core B and the adapter A is butt-welded. When the twocomponents of the fixed core B and the adapter A are butted, a gap 502is formed by digging a corner of the fixed core B as illustrated suchthat butt surfaces 501 come into close contact with each other orchamfering a corner of the adapter A although not illustrated. When thebutt portion is welded, laser welding is performed such that the meltedportion has a shape as illustrated by 503B in order to completely fillthe gap 502 with molten metal.

The reason why the gap 502 is completely filled with the molten metal isbecause the stress increases depending on a shape of the gap when a loadin the arrow direction in the drawing is applied to the component B,which may reduce the strength of the welded portion. That is, there is apossibility that the welded portion shape 504 protruding into such anabutting gap causes stress concentration even in the butt welding. Suchan example is illustrated in FIG. 5B.

FIG. 5B is an enlarged cross-sectional view of a welded portion betweena first component A and a second component B according to ComparativeExample 3 of the present invention.

In the case of a shape of the welded portion as illustrated in FIG. 5B,there is a possibility that a part 504 of metal 503E after melting andre-solidifying locally swells to protrude into a gap 502 between thefirst component A and the second component B. Since an angle θ1 formedby the welded portion shape 504 is small with respect to an axial load510 caused by the fuel pressure, this gap shape causes stressconcentration to increase the stress, which reduces the strength of thewelded portion 503E.

On the other hand, a distal end portion (innermost portion) in a weldingdirection (welding depth direction) is formed to be located on the innerside in the welding direction (the e right side in FIG. 5A) with respectto a press-fitting portion (a boundary portion between a press-fittingportion inner peripheral surface A1 of the first component A and apress-fitting portion outer peripheral surface B1 of the secondcomponent B) as in butt-welded portions 503B, 503C, and 503D in FIG. 5A.The welded portions 503B, 503C, and 503D are formed so as to fill allgaps formed between the first component A and the second component Bbefore welding. As a result, it is possible to suppress reduction instrength of the welded portions 503B, 503C, and 503D caused by theincrease in stress due to the shape of the gap 502.

Note that a weld penetration depth WD1 varies with respect to anintended target in the manufacturing process. Even if welding isperformed with a penetration shape of 503B as a target, there is apossibility that a penetration shape 503A smaller than that is actuallyobtained to leave the gap 502 after welding. Accordingly, in order tofill the entire gap 502 with the molten metal, a weld shape 503C is setas a target such that a weld shape 503B can be ensured even ifvariations occur and the penetration depth becomes small.

Meanwhile, coaxial accuracy is required in the fuel injection valve,there is a demand for minimization of heat input during welding. In thecase of the weld shape illustrated in FIG. 5A, it is conceivable thatthe penetration is set to 608 having larger penetration in considerationof the occurrence of variations described above even when a penetrationshape of 503C is set as the target. However, when ⅔ or more of athickness T1 of the component B is melted, a deformation amount duringwelding becomes large, so that the coaxial accuracy of the fuelinjection valve is likely to deteriorate.

FIG. 5C is an enlarged cross-sectional view of a welded portion betweena first component A and a second component B according to ComparativeExample 4 of the present invention.

FIG. 5C illustrates a shape of the welded portion when a penetrationdepth of butt welding is WD2 in order to suppress deterioration ofcoaxial accuracy. When the penetration depth WD2 equal to or shorterthan an abutting length is set, it is clear that an end portion 505 of awelded portion shape causes stress concentration in a load directionindicated by the arrow. Accordingly, when a weld penetration shape ismade shorter than the butt length in butt welding, there is apossibility that it is difficult to ensure sufficient rigidity andstrength against a load generated by a high fuel pressure.

Typically, a lubricant is used at the time of press-fitting twocomponents in order to prevent galling, reduce a load at the time ofpress fitting, and reliably bringing abutting portions of the twocomponents in contact with each other. The influence of the lubricantwill be described with reference to FIGS. 6 and 5A.

FIG. 6 is an enlarged cross-sectional view illustrating a state beforepress fitting of a fixed core 607 and an adapter 640 according toComparative Example 5 of the present invention.

The lubricant can be applied to either an inner diameter of the adapter(first component) 640 or an outer diameter of the fixed core (secondcomponent) 607, but it is easy and inexpensive to apply the lubricant toa range indicated by 601 on an outer diameter portion of the fixed core607 as illustrated in FIG. 6A. Before press-fitting the adapter 640 andthe fixed core 607, an axial deviation E1 between both the components ismade as small as possible, but it is industrially difficult tocompletely set the axial deviation E1 to zero. Accordingly, a beakportion (small diameter portion) 602 having an outer diameter slightlysmaller than a press-fitting diameter D1 is provided on the upstreamside (upper end side) of the press-fitting portion of the fixed core607.

Even if there is the axial deviation E1 between the two components, thebeak portion 602 is often used industrially since the amount of theaxial deviation can be made equal to or smaller than a differencebetween the press-fitting diameter D1 and a peak diameter D2 as the twocomponents are guided to each other. However, since a step between thebeak portion 602 and a press-fitting portion 603 is small (for example,about 0.04 mm), the amount of the axial deviation E1 between both thecomponents is larger before the press fitting. In this case, there is apossibility that the lubricant having adhered to the beak portion 602even adheres to a portion 604 to be welded after abutment. At the timeof welding, molten metal has a shape like 503A, 503B, 503C, and 503D inFIG. 5A, and thus, if the adhering lubricant is directly heated by alaser, the heated lubricant is gasified to generate blowholes.

When the fixed core 607 and the adapter 640 of FIG. 6 are press-fitted,the state illustrated in FIG. 5A is obtained.

Note that the adapter 640 corresponds to the first component A in FIG.5A, and the fixed core 607 corresponds to the second component B in FIG.5A. When the fixed core 607 and the adapter 640 are press-fitted, thelubricant is pushed downward in the drawing and is accumulated in thegap 502. Since the molten metal has a shape like 503A, 503B, 503C, and503D at the time of welding, the lubricant accumulated in the gap 502 isdirectly heated. The heated lubricant is gasified to generate blowholes.

FIG. 7 is an enlarged cross-sectional view of a welded portion between afirst component A and a second component B according to ComparativeExample 6 of the present invention.

Even when a chamfer 701 is provided on the first component A in order toprevent a lubricant from entering the welded portion and a gap 702larger than the conventional one is provided as illustrated in FIG. 7,molten metal has a shape like 703 at the time of welding, and thus, thelubricant accumulated in the gap 702 is directly heated so that there isa possibility that the heated lubricant is gasified to generateblowholes. Further, even if the lubricant does not come into contactwith the welded portion 703 and no blowhole is generated, an angle θ2formed by a base metal and the welded portion 703 is smaller than 90degrees, so that there is a possibility that stress increases andstrength decreases. Note that 704 denotes a butt surface (butt-weldedportion), and 705 denotes a central portion in a direction (up-and-downdirection in FIG. 7) orthogonal to a welding depth direction of thebutt-welded portion 704 (the right direction in FIG. 7).

As described above, it is difficult to completely eliminate the axialdeviation during assembly in the butt-welded portion in theconfigurations like the comparative examples, and blowholes are likelyto be generated due to the applied lubricant in the configurations. Evenif no blowhole is generated, the angle between the base metal and thewelded portion is smaller than 90 degrees, so that the strength islikely to decrease in the configurations. The present embodimentproposes the configuration (shape) of the welded portion in whichblowholes caused by the lubricant are less likely to be generated, andthe strength is less likely to decrease.

FIG. 8 is an enlarged cross-sectional view of the welded portion betweenthe adapter 140 and the fixed core 107 according to the embodiment ofthe present invention.

In the present embodiment, the adapter 140 and the fixed core 107 arebutted to perform butt welding.

The mounting portion 301 is formed at the lower end portion (the endportion on the fixed core 107 side) of the adapter 140. An outerperipheral surface 301A of the mounting portion 301 has the samediameter as an outer peripheral surface 140A of the adapter 140. A firstinner peripheral surface 301B of the mounting portion 301 is enlarged indiameter with respect to an inner peripheral surface 140B on theupstream side of the adapter 140 so as to have an inner diameter largerthan an inner diameter φCn on the upstream side of the adapter 140. Thatis, a radial step surface 301G is formed between the first innerperipheral surface 301B of the mounting portion 301 and the innerperipheral surface 140B of the adapter 140.

Further, a second inner peripheral surface 301C having a larger diameterthan the first inner peripheral surface 301B is formed at a lower endportion of the mounting portion 301. The second inner peripheral surface301C is enlarged in diameter with respect to the first inner peripheralsurface 301B, and a radial step surface 301D is formed between the firstinner peripheral surface 301B and the second inner peripheral surface301C.

The mounting portion 302 is formed at the upper end portion (the endportion on the adapter 140 side) of the fixed core 107. An innerperipheral surface 302A of the mounting portion 302 has the samediameter as an inner peripheral surface 107F of the fixed core 107. Afirst outer peripheral surface 302B of the mounting portion 302 isreduced in diameter with respect to an outer peripheral surface 107E onthe downstream side of the fixed core 107 so as to have an outerdiameter smaller than an outer diameter on the downstream side of thefixed core 107. That is, radial step surfaces 302F and 302D are formedbetween the first outer peripheral surface 302B of the mounting portion302 and the outer peripheral surface 107E of the fixed core 107.

Further, a second outer peripheral surface 302C having a larger diameterthan the first outer peripheral surface 302B is formed at a lower endportion of the mounting portion 302. The second outer peripheral surface302C is enlarged in diameter with respect to the first outer peripheralsurface 302B, and the radial step surface 302D is formed between thefirst outer peripheral surface 302B and the second outer peripheralsurface 302C.

A lower end surface 301F of the mounting portion 301 and the stepsurface 302F of the mounting portion 302 oppose each other, and the stepsurface 301G of the mounting portion 301 and an upper end surface 302Gof the mounting portion 302 oppose each other. The lower end surface301F of the mounting portion 301 and the step surface 302F of themounting portion 302 abut on each other, but a gap is provided betweenthe step surface 301G of the mounting portion 301 and the upper endsurface 302G of the mounting portion 302. Furthermore, the first outerperipheral surface 302B, the step surface 302D, and the second outerperipheral surface 302C of the mounting portion 302 oppose the firstinner peripheral surface 301B, the step surface 301D, and the secondinner peripheral surface 301C of the mounting portion 301, respectively.

Note that a chamfer 301E is provided between the first inner peripheralsurface 301B of the mounting portion 301 and the step surface 301D.Further, a beak portion 302E is provided at an upper end portion of thefirst outer peripheral surface 302B of the mounting portion 302. Thechamfer 301E and the beak portion 302E have the same functions as thechamfer 701 and the beak portion 602 described in the comparativeexamples.

At a site where the chamfer 301E of the mounting portion 301 and thefirst outer peripheral surface 302B of the mounting portion 302 opposeeach other in the radial direction, an inner diameter of the chamfer301E of the mounting portion 301 is larger than an outer diameter of thefirst outer peripheral surface 302B of the mounting portion 302, and isenlarged in diameter downward. Further, at a site where the second innerperipheral surface 301C of the mounting portion 301 and the second outerperipheral surface 302C of the mounting portion 302 oppose each other inthe radial direction, an inner diameter of the second inner peripheralsurface 301C of the mounting portion 301 is larger than an outerdiameter of the second outer peripheral surface 302C of the mountingportion 302.

Reference sign 803 represents a shape of the welded portion in whichmetal melted by welding is re-solidified. That is, the fuel injectionvalve 1 of the present embodiment includes the adapter (first component)140 and the fixed core (second component) 107 that are press-fitted andbutt-welded to each other.

Further, an abutting surface (butt surface) 801 are formed between thelower end surface 301F of the mounting portion 301 of the firstcomponent 140 and the step surface 302F of the mounting portion 302 ofthe second component 107 to come into contact with both the lower endsurface 301F and the step surface 302F, and the butt-welded portion 803is formed along the abutting surface on this abutting surface 801.

The mounting portion 301 of the adapter 140 and the mounting portion 302of the fixed core 107 are press-fitted so as to be pressed against eachother in the radial direction, thereby forming a press-fitting fittingportion 802. That is, the mounting portion 301 of the adapter 140 andthe mounting portion 302 of the fixed core 107 are firmly fixed by thebutt-welded portion 803 in addition to the press-fitting portion 802.

In the configuration illustrated in FIG. 4, there is a possibility thatthe fixing strength is insufficient due to the stress concentration. Inthe present embodiment, however, the butt surface 801 between theadapter 140 and the fixed core 107 is perpendicular to the main loaddirection indicated by the arrow. Accordingly, the load is appliedsubstantially uniformly on the entire butt surface 801, and the maximumstress thus generated is smaller than that in the lap weldingillustrated in FIG. 4. Therefore, the present embodiment can improve thefixing strength.

As a result, the butt-welded portion 803 is welded so as to have thestrength capable of withstanding a high fuel pressure load. The buttwelding has a higher joint efficiency than the lap welding that isperformed by the conventional fuel injection valve, so that the strengthis improved for the same penetration amount.

FIG. 9 illustrates an example of applying the lubricant in the presentembodiment. FIG. 9 is an enlarged cross-sectional view illustrating astate before press fitting of the fixed core 107 and the adapter 140according to the embodiment of the present invention.

The lubricant can be applied to either the inner diameter (innercircumference) of the first component 140 or the outer diameter (outercircumference) of the second component 107, but it is industrially easyand inexpensive to apply the lubricant to the outer diameter of thesecond component 107. In the present embodiment, the lubricant isapplied to a portion indicated by 901. That is, the lubricant is appliedto an upper end portion including the beak portion 302E on the firstouter peripheral surface 302B of the mounting portion 302 of the secondcomponent 107.

Before press-fitting the first component 140 and the second component107, the axial deviation E1 between both the components is made as smallas possible, but it is industrially difficult to completely eliminatethe axial deviation E1. Accordingly, the beak portion 302E having theouter diameter slightly smaller than the press-fitting diameter isprovided at the upper end portion of the press-fitting portion 302 ofthe second component 107. In the present embodiment, the step 301D (forexample, about 0.5 mm in the radial direction) that is larger than theaxial deviation E1 between both the components before the press fittingis provided between the press-fitting fitting portion 802 and the weldedportion 803 of the adapter 140. Accordingly, the lubricant applied tothe beak portion 302E does not adhere to the welded portion 803 afterbeing abutted. Accordingly, it is possible to suppress the generation ofblowholes at the time of welding in which the lubricant is heated by thelaser.

This will be described with reference to FIG. 10 together with FIG. 9.FIG. 10 is an enlarged cross-sectional view of the welded portionbetween the adapter 140 and the fixed core 107 according to theembodiment of the present invention. Note that FIG. 10 is an enlargedview of part X of FIG. 8.

A first gap 1001 is formed by the first component 140 and the secondcomponent 107 between the press-fitting fitting portion 802 of the firstcomponent 140 and the second component 107 and the butt-welded portion803, and a second gap 1002 is formed by the first component 140 and thesecond component 107 between the first gap 1001 and the butt-weldedportion 803. That is, the first gap 1001 and the second gap 1002 areformed between the chamfer 301E, the step surface 301D, and the secondinner peripheral surface 301C of the mounting portion 301, and the firstouter peripheral surface 302B, the step surface 302D, and the secondouter peripheral surface 302C of the mounting portion 302.

Note that a chamfer 301E is provided between the first inner peripheralsurface 301B of the mounting portion 301 and the step surface 301D.

In FIG. 10, as an example, the first gap 1001 is formed in a direction(radial direction) intersecting a direction of the press-fitting fitting802 (direction of the central axis 1 a), and the second gap 1002 isformed in a direction intersecting the first gap 1001 (direction of thecentral axis 1 a).

Further, the volume of the first gap 1001 is larger than the volume ofthe second gap 1002.

Although the lubricant is pushed downward in the drawing at the time ofpress-fitting the adapter 140 and the fixed core 107, the possibilitythat the lubricant flows into the second gap 1002 is low since thevolume of the first gap 411 is larger than the volume of the lubricantadhering to the beak portion 512 and the press-fitting fitting portion802. Even if the lubricant tries to flow into the second gap 1002, thepossibility that the lubricant enters the abutting portion 801 beyondthe second gap 1002 is extremely low since the flow path resistance isincreased by reducing an interval of the second gap 1002 with respect tothe first gap 1001. The volume of the lubricant adhering to the beakportion 302E and the press-fitting fitting portion 802 can be calculatedby multiplying an application area by a membrane thickness of thelubricant. The membrane thickness of the lubricant can be experimentallymeasured in advance. A specific numerical value of this membranethickness is, for example, about 5 μm.

In the manufacturing process, the lubricant can be prevented fromentering the abutting portion 801 due to gravity by setting a directionopposite to the direction illustrated in FIG. 9 (upside down). In thepresent embodiment, the lubricant does not adhere to the abuttingportion 801 when the adapter 140 and the fixed core 107 arepress-fitted, and it is possible to suppress the generation of blowholesat the time of welding.

Next, the reason why the strength of the welded portion 803 of thepresent embodiment increases will be described with reference to FIG.10.

In the present embodiment, a boundary between the high-pressure fuel andthe atmosphere is constituted by two or more components including thefirst component A and the second component B. The first component A andthe second component B are fitted and press-fitted by thesmall-diameter-side outer diameter 302B of the second component Bprovided with a stepped portion on the outer diameter side (outerperipheral side), and the large-diameter-side inner diameter 301B of thefirst component A provided with a stepped portion on the inner diameterside (inner peripheral side), and come into contact with each other atthe abutting surface 801 to be positioned. The stepped portion of thefirst component A and the stepped portion of the second component B areformed such that an interval is provided therebetween and surfacesforming both the stepped portions are located along each other. Thefirst component A corresponds to the adapter 140 or the mounting portion401 of the adapter 140, and the second component B corresponds to thefixed core 107 or the mounting portion 402 of the fixed core 107. Thebutt welding is performed from a direction parallel or substantiallyparallel to the abutting surface 801 between the first component A andthe second component B to form the butt-welded portion 803.

The butt-welded portion 803 is formed such that a weld joint length L2is larger than an abutting length L1 between the first component A andthe second component B. Further, a weld penetration depth L4 of thebutt-welded portion 803 is set to be equal to or longer than a length L3between the outer peripheral surface of the fixed core 107 and thesecond outer peripheral surface 302C of the mounting portion 302 so asto reach a step portion 302C of the second component B. Since there isan industrial variation in the penetration depth at the time of welding,melting is actually performed up to the position of L4. A weldpenetration center 803 a is located closer to a component arranged onthe outer peripheral side of the press-fitting portion 802 than theabutting surface 507. That is, the center 803 a in a direction(up-and-down direction in FIG. 6A) orthogonal to the welding directionof the butt-welded portion 803 (right direction in FIG. 10) is locatedcloser to the first component A than the abutting surface 801.

A case where the welding center position 803 a deviates from a targetposition toward the second component B in the drawing will be describedwith reference to FIG. 11. FIG. 11 is an enlarged cross-sectional viewof a welded portion between an adapter 140 and a fixed core 107according to Comparative Example 7 of the present invention.

In Comparative Example 7, an angle θ4 formed by a butt-welded portion1103, which is melted and re-solidified metal after welding, and a firstcomponent A is small. Therefore, stress generated in the welded portion1103 becomes large, and strength of the welded portion 1103 is reduced.As above, a weld penetration center 1103 a needs to be located closer tothe first component A than an abutting surface 801.

The description will be given with reference to FIG. 10 again. An angleis θ3, the angle formed by a tangent line 1004 in contact with a surface803 b of the butt-welded portion 803 and a tangent line 1005 drawn onthe second inner peripheral surface 301C at a position 1003 where thesurface 803 b of the butt-welded portion 803, which is melted andre-solidified metal, intersect a first member A, that is, at theposition 1003 of an end portion having the weld joint length L2 on thesurface 803 b of the butt-welded portion 803, alternatively, at anintersection 1003 between the surface 803 b of the butt-welded portion803 and the second inner peripheral surface 301C forming the second gap1002.

Since the angle θ3 of the present embodiment is larger than the angle θ2of Comparative Example 6 illustrated in FIG. 7, the increase in stressdue to the stress concentration is reduced, and the strength of thewelded portion 803 can be maintained. Note that it is possible tomaintain desired fixing strength in the fuel injection valve 1 if theangle θ3 is, for example, 90 degrees or larger, and the angle θ3 islarger than 90 degrees. A modification of the present embodiment will bedescribed with reference to FIG. 12. FIG. 12 is an enlargedcross-sectional view of a welded portion between the adapter 140 and thefixed core 107 according to the modification of the present invention.

It is preferable that an angle θ6 formed by a tangent line 1203 and theabutting surface 801 be small in order to maximize an angle θ5 formedbetween a tangent line 1202 of an upper surface portion 1201 b of thebutt-welded portion 803 and the second inner peripheral surface 301Cforming the second gap 1002 or the tangent line 1203 of the second innerperipheral surface 301C. However, the second gap 1002 needs to be smallin order to prevent lubricant from entering a welded portion 1201, andit is necessary for the first component A and the second component B notto interfere with each other to press-fit both the components, and thus,θ5 and θ6 are set to about 90 degrees.

The first gap 1001 and the second gap 1002 will be described withreference to FIG. 13. FIG. 13 is a conceptual view illustrating aconfiguration of the first gap 1001 and the second gap 1002. Note thatFIG. 13 is a plan view that includes the central axis 1 a and isparallel to the central axis 1 a.

In FIG. 13, a y-axis and an x-axis are defined as described in thedrawing. The y-axis is on the same plane as the central axis 1 a and isparallel to the central axis 1 a. The x-axis is on the same plane as they-axis and the central axis 1 a, and is parallel to the radialdirection.

In the present embodiment, a straight portion is formed in each of thestep surface 301D and the step surface 302D forming the first gap 1001in FIG. 13. In this case, a straight line segment 1301 extended from astraight portion 1303 of the step surface 302D serves as a boundary thatdivides the first gap 1001 and the second gap 1002. That is, the firstgap 1001 extends from the straight line segment 1301 toward thepress-fitting portion 802, and the second gap 1002 is located on theside of the abutting portion (abutting surface) 801 or the butt-weldedportion 803 with respect to the straight line segment 1301.

If the straight portion 1303 of the step surface 302D is notidentifiable, the boundary between the first gap 1001 and the second gap1002 may be identified based on a center line 300 passing throughcenters of the first gap 1001 and the second gap 1002. The center line300 is a line segment, which connects points where the distance from theadapter 140 and the distance from the fixed core 107 are equal, on astraight line segment connecting the adapter 140, which is the firstcomponent A, and the fixed core 107, which is the second component B,with the shortest distance in FIG. 13, and is a bent line segment asillustrated in FIG. 13. In the present embodiment, there are two bentportions in the first gap 1001 and the second gap 1002. Note that thesecond gap 1002 inside the butt-welded portion 803 is filled with themolten metal and does not exist as a gap. At points P1 to P6 on thecenter line 300, unit vectors V1 to V6 in contact with the center line300 are set. At each of the points P1 to P6, each magnitude of an x-axiscomponent and a y-axis component of the unit vectors V1 to V6 changes.At the point P3, the y-axis component becomes zero and the magnitude ofthe x-axis component becomes one. That is, it can be understood that aradial gap is formed at the point P3. That is, it can be understood thata radial gap is formed at the point P3. On the other hand, the x-axiscomponent becomes zero and the magnitude of the y-axis component becomesone at the point P6. That is, it can be understood that a gap is formedin the direction of the central axis 1 a at the point P6. At the pointsP2 and P4, the magnitude of the x-axis component and the magnitude ofthe y-axis component become equal. In this case, the boundary betweenthe first gap 1001 and the second gap 1002 may be identified using P4,as a reference, at which the radial gap changes to the gap formed in thedirection of the central axis 1 a. That is, a straight line segment LnP4passing through P4 and connecting the adapter 140 and the fixed core 107with the shortest distance is set as the boundary. The first gap 1001extends from the straight line segment LnP4 toward the press-fittingportion 802, and the second gap 1002 is located on the side of theabutting portion (abutting surface) 801 or the butt-welded portion 803with respect to the straight line segment LnP4.

Alternatively, a straight portion is formed on each of the second innerperipheral surface 301C and the second outer peripheral surface 302Cforming the second gap 1002 in the present embodiment. If the straightportion 1303 of the step surface 302D is not identifiable, the boundarybetween the first gap 1001 and the second gap 1002 may be identifiedbased on a straight portion 1304 of the second outer peripheral surface302C. In this case, in FIG. 13, an intersection P5 between a straightline segment 1302 extended from the straight portion 1304 and the centerline 300 is determined, and a straight line segment LnP5, which passesthrough the intersection P5 and connects the adapter 140 and the fixedcore 107 with the shortest distance, is defined as the boundary thatdivides the first gap 1001 and the second gap 1002. The first gap 1001extends from the straight line segment LnP5 toward the press-fittingportion 802, and the second gap 1002 is located on the side of theabutting portion (abutting surface) 801 or the butt-welded portion 803with respect to the straight line segment LnP5.

As described above, the component of the present embodiment includes:the first component 140 (A); the second component 107 (B) fixed to thefirst component 140 (A) by the press-fitting portion 802; the weldedportion 803 that connects the first component 140 (A) and the secondcomponent 107 (B); and the first gap 1001 and the second gap 1002 formedbetween the mutually opposing surfaces of the first component 140 (A)and the second component 107 (B). The first gap 1001 is provided betweenthe press-fitting portion 802 and the welded portion 803 on thepress-fitting portion 802 side with respect to the second gap 1002, andis formed in the direction intersecting the press-fitting direction. Thesecond gap 1002 is provided between the press-fitting portion 802 andthe welded portion 803 on the welded portion 803 side with respect tothe first gap 1001, and is formed in the direction intersecting thefirst gap 1001.

The welded portion 803 is the butt-welded portion having the butt-jointconfiguration, the first gap 1001 is connected to the press-fittingportion 802, and the second gap 1002 is connected to the butt-weldedportion 803.

The first component 140 (A) includes a first-component-side steppedportion having the large-diameter inner peripheral surface 301C and thesmall-diameter inner peripheral surface 301B on the inner peripheralside. The second component 107 (B) includes a second-component-sidestepped portion having the large-diameter outer peripheral surface 107E,the medium-diameter outer peripheral surface 302C, and thesmall-diameter outer peripheral surface 302B on the outer peripheralside. The press-fitting portion 802 is formed between the small-diameterinner peripheral surface 301B of the first component 140 (A) and thesmall-diameter outer peripheral surface 302B of the second component 107(B). The butt-welded portion 803 is formed between the first componentend surface 301F, formed between the outer peripheral surface 140A andthe large-diameter inner peripheral surface 301C of the first component140 (A), and the second component first step surface 302F formed betweenthe large-diameter outer peripheral surface 107E and the medium-diameterouter peripheral surface 302C of the second component 107 (B).

The first gap 1001 is formed between the first component step surface301D, formed between the large-diameter inner peripheral surface 301Cand the small-diameter inner peripheral surface 301B of the firstcomponent 140 (A), and the second component second step surface 302Dformed between the medium-diameter outer peripheral surface 302C and thesmall-diameter outer peripheral surface 302B of the second component 107(B). The second gap 1002 is formed between the large-diameter innerperipheral surface 301C of the first component 140 (A) and themedium-diameter outer peripheral surface 302C of the second component107 (B).

The minimum interval L5 of the first gap 1001 in the press-fittingdirection (direction of the central axis 1 a) is configured to be largerthan the minimum interval L6 of the second gap 1002 in the direction(radial direction) intersecting the press-fitting direction. The volumeof the first gap 1001 is configured to be larger than the volume of thesecond gap 1002. The deepest portion L4 in the welding depth directionof the butt-welded portion is configured to be located on the side wherethe welding depth becomes deeper with respect to the second gap 1002.

The first gap 1001 is configured to have the elongated shape such thatthe length in the direction (radial direction) intersecting thepress-fitting direction is longer than the interval L5 formed betweenthe mutually opposing surfaces of the first component 140 (A) and thesecond component 107 (B). The second gap 1002 is configured to have theelongated shape such that the length in the press-fitting direction(direction of the central axis 1 a) is longer than the interval formedbetween the mutually opposing surfaces of the first component 140 (A)and the second component 107 (B).

The fuel injection valve of the present embodiment includes: the fixedcore 107; the movable core 102 and the valve body 114A driven by themagnetic attraction force of the fixed core 107; the fuel injection hole117 for injecting fuel when the valve body 114A is separated from thevalve seat 39; and the adapter 140 connected to the fixed core 107 toform the fuel supply port 118. The fixed core 107 is configured usingthe second component A, and the adapter 140 is configured using thefirst component A.

The weld shape of the present embodiment illustrated in FIG. 10 has anadvantage that the first component A and the second component B are notrequired to have complicated shapes and the manufacturing cost of thecomponents is not increased. Further, it is unnecessary to change aposition and an angle of the penetration center 803 a during laserwelding, there is an advantage that cost of welding equipment is notincreased. Further, the welding time can be shortened since the positionand angle of the penetration center 803 a are not changed during laserwelding.

As above, according to the embodiment of the present invention, it ispossible to suppress the generation of blowholes at the time of weldingin the site where the lubricant is used for press fitting, and tominimize the amount of penetration of the butt-welded portion. Further,the welding time and the cost of welding equipment can be reduced in thepresent embodiment. Furthermore, it is possible to realize the buttwelding configuration capable of suppressing the excessive stressconcentration with respect to the load in the present embodiment.

Note that the present invention is not limited to the above-describedembodiment, but includes various modifications.

For example, the above-described embodiment has been described in detailin order to describe the present invention in an easily understandablemanner, and are not necessarily limited to one including the entireconfiguration that has been described above. Further, a part of theconfiguration of the embodiment can be deleted or replaced with anotherconfiguration, and another configuration can be added to theconfiguration of the embodiment.

REFERENCE SIGNS LIST

-   39 valve seat-   102 movable core-   107 fixed core-   107E large-diameter outer peripheral surface-   114A valve body-   117 fuel injection hole-   118 fuel supply port-   140 adapter-   301B small-diameter inner peripheral surface-   301C large-diameter inner peripheral surface-   301B, 301C first-component-side stepped portion-   301D first component step surface-   301F first component end surface-   302B small-diameter outer peripheral surface-   302C medium-diameter outer peripheral surface-   302D second component second step surface-   302B, 302C, 302E second-component-side stepped portion-   302F second component first step surface-   802 press-fitting portion-   803 butt-welded portion-   1001 first gap-   1002 second gap-   A first component-   B second component

The invention claimed is:
 1. A component for a flow rate control devicecomprising: a first component; a second component fixed to the firstcomponent by a press-fitting portion; a welded portion that connects thefirst component and the second component; and a first gap and a secondgap formed between mutually opposing surfaces of the first component andthe second component, wherein the first gap is provided on a side of thepress-fitting portion with respect to the second gap between thepress-fitting portion and the welded portion, and is formed in adirection intersecting a press-fitting direction, and the second gap isprovided on a side of the welded portion with respect to the first gapbetween the press fitting portion and the welded portion, and is formedin a direction intersecting the first gap, wherein the welded portion isa butt-welded portion having a butt-joint configuration, and the firstgap is connected to the press-fitting portion, and the second gap isconnected to the butt-welded portion, wherein a volume of the first gapis configured to be larger than a volume of the second gap, wherein thefirst gap extends in a radial direction, and the second gap extends in avertical direction perpendicular to the radial direction.
 2. Thecomponent for a flow rate control device according to claim 1, whereinthe first component includes a first-component-side stepped portionhaving a large-diameter inner peripheral surface and a small-diameterinner peripheral surface on an inner peripheral side, the secondcomponent includes a second-component-side stepped portion having alarge-diameter outer peripheral surface, a medium-diameter outerperipheral surface, and a small-diameter outer peripheral surface on anouter peripheral side, the press-fitting portion is formed between thesmall-diameter inner peripheral surface of the first component and thesmall-diameter outer peripheral surface of the second component, and thebutt-welded portion is formed between a first component end surface,formed between an outer peripheral surface and the large-diameter innerperipheral surface of the first component, and a second component firststep surface formed between the large-diameter outer peripheral surfaceand the medium-diameter outer peripheral surface of the secondcomponent.
 3. The component for a flow rate control device according toclaim 2, wherein the first gap is formed between a first component stepsurface, formed between the large-diameter inner peripheral surface andthe small-diameter inner peripheral surface of the first component, anda second component second step surface formed between themedium-diameter outer peripheral surface and the small-diameter outerperipheral surface of the second component, and the second gap is formedbetween the large-diameter inner peripheral surface of the firstcomponent and the medium-diameter outer peripheral surface of the secondcomponent.
 4. The component for a flow rate control device according toclaim 1, wherein a minimum interval of the first gap in thepress-fitting direction is configured to be larger than a minimuminterval of the second gap in the direction intersecting thepress-fitting direction.
 5. The component for a flow rate control deviceaccording to claim 1, wherein a deepest portion in a welding depthdirection of the butt-welded portion is configured to be located on aside where a welding depth becomes deeper with respect to the secondgap.
 6. The component for a flow rate control device according to claim1, wherein the first gap is configured to have an elongated shape suchthat a length in the direction intersecting the press-fitting directionis longer than an interval formed between the mutually opposing surfacesof the first component and the second component.
 7. The component for aflow rate control device according to claim 1, wherein the second gap isconfigured to have an elongated shape such that a length in thepress-fitting direction is longer than an interval formed between themutually opposing surfaces of the first component and the secondcomponent.
 8. A fuel injection valve comprising: a fixed core; a movablecore and a valve body driven by a magnetic attraction force of the fixedcore; a fuel injection hole for injecting fuel when the valve body isseparated from a valve seat; and an adapter connected to the fixed coreto form a fuel supply port, wherein the fixed core and the adapter areconfigured using the component for a flow rate control device accordingto claim 1 such that the fixed core is provided as the second componentand the adapter is provided as the first component.
 9. The component fora flow rate control device according to claim 1, wherein an angle formedby a first tangent line tangent with an upper surface of the butt-weldedportion, and a second tangent line tangent to the vertical direction, is90 degrees or larger.